Previous studies with Li.sub.x CoO.sub.2 (0&lt;.times.&lt;1) cathodes in a lithium rechargeable electrochemical cell have demonstrated the practicality of such a cathode. The initial studies found that the layered rock salt structure of Li.sub.x CoO.sub.2 could intercalate one mole of lithium per mole of cobalt at voltages of 4 V or greater, and theoretically was capable of providing energy densities in excess of 1000 Wh/kg. However, it was found that the cell could not be fully charged due to electrolyte decomposition at the higher charging potentials of greater than 4 V. Due to this limitation in charging, the practical configuration of the Li/Li.sub.x Co.sub.2 cell was limited to only half of the theoretical energy density. For example, the most promising Li/Li.sub.x CoO.sub.2 rechargeable cell used an electrolyte of LiAsF.sub.6 in methylacetate (MA), and cycling between 2.5 V and 4.3 V resulted in energy densities from 400 to 500 Wh/kg over 20 cycles. These results were obtained at 25.degree. C. and discharge and charge rates of 1.0 mA/cm.sup.2 and 0.5 mA/cm.sup.2 respectively.